How fast is Mach 5?
Mach 5 equals 5 times the speed of sound. As the speed of sound is variable according to air density Mach 5 is also variable.
Close! Actually, Mach-1 is the speed of sound. anything above Mach-1 (Mach-(1-5)) is supersonic, all the way up to Mach-5, at which point an object is called "Hypersonic". Sometimes speeds above Mach-10 are referred to as "High-Hypersonic". So, a jet moving at Mach-1 wouldn't actually be traveling FASTER than sound, it would be traveling AS FAST as sound.